Move over nymphal ticks, larval deer ticks now pose a threat

The blacklegged tick has four life stages - egg, larva, nymph and adult. After it hatches, the tick must eat a blood meal (host) at every stage in order to survive. Researchers have long believed that adult female ticks could not transfer pathogens to their eggs. Therefore, larval ticks were considered pathogen-free and harmless. A new study, however, sheds light on disease transmission between life stages and suggests that we take these tiny, microscopic larvae a bit more seriously.

According to investigators from the Centers for Disease Control and Prevention (CDC), larval ticks can already be infected with Borrelia miyamotoi, after they hatch from the eggs. [1] This occurs through a process called transovarially transmission in which the adult tick transmits the B. miyamotoi bacteria to its offspring by infecting the eggs in its ovary.

There is evidence that infected blacklegged female ticks can pass Borrelia miyamotoi to their offspring, researchers say.

Researchers infected experimental mice with Borrelia miyamotoi, the relapsing fever bacteria. They found that “minimal or partial blood meals by single-feeding transovarially B. miyamotoi-infected larvae also resulted in approximately half of experimental hosts developing infections detectable by examination of blood for presence of B. miyamotoi DNA,” writes Breuner from the CDC’s National Center for Emerging and Zoonotic Infectious Diseases.

Larval ticks need to be taken seriously, as new research finds they can transmit the relapsing fever spirochete Borrelia miyamotoi. Click To Tweet

The authors suggest that public health officials consider revising the message for tick bite prevention campaigns to include larval ticks and the season they are most active – July and August. This is a time of year when people spend a lot of time outdoors, the authors state, and may be less vigilant protecting themselves from tick bites, as they mistakenly perceive this to be a safer season.


Related Articles:

Larval ticks may be a threat after all – insights based on study of B. miyamotoi 

Study demonstrates further evidence larval ticks may be a threat to humans

Will eliminating deer help stop the spread of infected ticks?



  1. Breuner NE, Hojgaard A, Replogle AJ, Boegler KA, Eisen L. Transmission of the relapsing fever spirochete, Borrelia miyamotoi, by single transovarially-infected larval Ixodes scapularis ticks. Ticks Tick Borne Dis. 2018.

8 Replies to "Move over nymphal ticks, larval deer ticks now pose a threat"

  • Aly
    09/23/2021 (7:37 pm)

    Hi Dr Cameron,
    Can a larvae deer tick transmit Lyme disease to a human? Thanks so much

    • Dr. Daniel Cameron
      09/24/2021 (7:46 am)

      Transovarially transmission has been considered in tick borne disease, that is the infection passes through the egg to the larva. I have not seen much research in this area.

  • Sophie Slater
    07/03/2021 (2:59 pm)

    Hi Dr. Cameron, I know this article is from a few years back, but thought I’d try my luck in getting in touch with you! Do you know what percentage of larval ticks are suspected of being infected with borrelia miyamotoi in states like CT? Thank you!

    • Dr. Daniel Cameron
      07/03/2021 (3:52 pm)

      I have not seen any information on how often Larval ticks harbor B. miyamotoi or B. burgdorferi.

      • Sophie Slater
        07/04/2021 (12:15 pm)

        Thank you!

  • Nicole
    10/21/2018 (2:33 pm)

    So if you have had chiggers could you have lyme or another tick borne illness?

  • Lane
    08/31/2018 (10:17 pm)

    Lone Stars also transmit some infections transovarially.

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